The Krapina white-tailed eagle talons represent a kind of jewelry worn by Krapina Neandertals some 130,000 years ago. New inspection of one Krapina talon (386.1) revealed a fiber, sealed by a thin silicate coating, adhering to the surface within a wide cut mark, as well as concentrated traces of occasional spots of red and yellow pigment and some black stains. We analyzed the fiber and small portions of pigmented areas by non-invasive, infrared synchrotron beam. Different areas were targeted, revealing the protein nature of the fiber, identified as of animal origin. Targeted areas revealed intra- and inter-strand aggregation indicating the fiber to be collagen losing its original triple α-helix conformation, further confirming the diagenetic decay of the original collagen structure and the antiquity of the fiber. It is possible that the fiber is a remnant of the leather or sinew string binding the talons together. Spectroscopic analysis of the pigments in two isolated areas confirmed two types of ochre and that the dark spots are charcoal remnants. Applying novel non-invasive technologies provides new possibilities to further test the hypothesis of using prehistoric objects for symbolic purposes.

Sediment-hosted CO2-rich aquifers deep below the Colorado Plateau (USA) contain a remarkable diversity of uncultivated microorganisms, including Candidate Phyla Radiation (CPR) bacteria that are putative symbionts unable to synthesize membrane lipids. The origin of organic carbon in these ecosystems is unknown and the source of CPR membrane lipids remains elusive. We collected cells from deep groundwater brought to the surface by eruptions of Crystal Geyser, sequenced the community, and analyzed the whole community lipidome over time. Characteristic stable carbon isotopic compositions of microbial lipids suggest that bacterial and archaeal CO2 fixation ongoing in the deep subsurface provides organic carbon for the complex communities that reside there. Coupled lipidomic-metagenomic analysis indicates that CPR bacteria lack complete lipid biosynthesis pathways but still possess regular lipid membranes. These lipids may therefore originate from other community members, which also adapt to high in situ pressure by increasing fatty acid unsaturation. An unusually high abundance of lysolipids attributed to CPR bacteria may represent an adaptation to membrane curvature stress induced by their small cell sizes. Our findings provide new insights into the carbon cycle in the deep subsurface and suggest the redistribution of lipids into putative symbionts within this community.

Biofilms are communities of bacteria living embedded in a highly hydrated matrix composed of polysaccharides, proteins, and extracellular DNA. This life style confers numerous advantages to bacteria including protection against external threats. However, they also contribute to increase bacterial resistance against antimicrobials, an issue particularly relevant in dangerous infections. Due to the complexity of the matrix, few information is present in the literature on details of its architecture including the spatial distribution of the macromolecular components which might give hints on the way the biofilm scaffold is built up by bacteria. In this study, we investigated the possibility to combine well-established microbiological procedures with advanced microscopies to get information on composition and distribution of the macromolecular components of biofilm matrices. To this, confocal microscopy, diffraction-limited infrared (IR) spectral imaging, and atomic force microscopy (AFM) were used to explore biofilm produced by a clinical strain of Klebsiella pneumoniae. IR imaging permitted to have clues on how the biofilm grows and spreads on surfaces, and the local distribution of the components within it. Through the analysis of the pure component spectra, it was possible to assess the chemical and structural composition of the saccaridic matrix, confirming the data obtained by NMR. It was also possible to follow the time course of biofilm from 6 up to 48 h when the biofilm grew into a 3-dimensional multi-layered structure, characteristic of colonies of bacteria linked together by a complex matrix. In addition, nanoFTIR and AFM investigations allowed the estimation of biofilm growth in the vertical direction and the morphological analysis of bacterial colonies at different time points and the evaluation of the chemical composition at the nanoscale.